Blunted sudomotor reactivity in fibromyalgia is associated with levels of depression.

OBJECTIVES: Assessment of sudomotor function by distal electrochemical skin conductance (ESC) can provide an index of peripheral neuropathy. This study explored ESC in fibromyalgia (FM) patients, controlling for tricyclic antidepressant use and body mass index, and its association with the clinical severity of the disease. METHODS: ESC, clinical symptoms and an index of central pain sensitisation derived from pressure algometry were explored in thirty-three fibromyalgia patients and 33 healthy women. RESULTS: ESC was significantly lower in fibromyalgia patients than healthy participants. About 51% of patients exhibited moderate-to-severe ESC dysfunction, indicative of possible neuropathy. However, ESC was not related to any indicators of clinical severity, nor to algometry. ESC only correlated with depression levels; the group differences in ESC disappeared after controlling for depression. Finally, ESC was asymmetric in the overall sample, with lower values seen in the right hand relative to the left one. CONCLUSIONS: The greater prevalence of sudomotor dysfunction in fibromyalgia patients is consistent with the presence of neuropathy in subgroups of patients, and with the basic heterogeneity of the disorder. However, neuropathy does not appear helpful for determining the clinical features of the disorders, or the level of central sensitisation measured by pressure algometry. Future studies including patients with fibromyalgia suffering and not suffering from depression as well as patients with depression but free from chronic pain, are required to identify the role of depression in the observed low ESC levels.

Central sensitisation pain and autonomic deficiencies in fibromyalgia.

OBJECTIVES: Fibromyalgia (FM) is associated with central pain sensitisation, autonomic alterations and neuropathy in small nerve fibres. This study aimed to analyse the association between tonic sweating and central pain sensitisation in FM. METHODS: Fifty-eight FM patients and thirty healthy women were assessed in terms of slowly repeated evoked pain (SREP), as a measure of central sensitisation. Sweating was evaluated by skin conductance (SC), as a sympathetic autonomic measure secondarily indexing possible small nerve fibre peripheral neuropathy. Clinical and psychological factors were evaluated through questionnaire measures. RESULTS: FM patients displayed smaller SC values than healthy controls, and SREP sensitisation was only observed in FM patients. Pain threshold and tolerance were also lower in the patient sample. Clinical symptoms (pain, fatigue, insomnia) only correlated significantly with SREP sensitisation. SC was inversely related to SREP sensitisation, and this association persisted after statistically controlling for levels of catastrophising and antidepressant use. CONCLUSIONS: These results suggest that central pain sensitisation, proposed as a main pathophysiological mechanism of FM, may depend on sympathetic autonomic deficiencies, suggestive of small nerve fibres neuropathy. Future studies should aim to replicate these results using other central pain sensitisation measures and direct measures of neuropathy or small nerve fibre density.

Addition of Slowly Repeated Evoked Pain Responses to Clinical Symptoms Enhances Fibromyalgia Diagnostic Accuracy.

OBJECTIVE: Fibromyalgia is a chronic pain syndrome characterized by central sensitization. A novel protocol based on slowly repeated evoked pain (SREP) appears to be a useful marker of pain sensitization in fibromyalgia patients. Whether SREP enhances diagnostic accuracy beyond key clinical symptoms that characterize fibromyalgia has not been examined. METHODS: Fifty fibromyalgia patients, 30 rheumatoid arthritis patients, and 50 healthy individuals were evaluated to assess clinical pain, as well as fatigue, insomnia, pain catastrophizing, and negative mood. The SREP protocol consisted of a series of nine low-intensity painful pressure stimuli of five seconds' duration with 30-second interstimulus intervals. SREP sensitization was indexed by increases in pain intensity ratings across stimuli. RESULTS: SREP sensitization was observed in fibromyalgia but not in rheumatoid arthritis or healthy individuals. As expected, fibromyalgia patients exhibited a more negative psychosocial profile than did rheumatoid arthritis patients and healthy individuals. SREP was positively associated with clinical pain, fatigue, insomnia, and catastrophizing, but not with negative mood. SREP discriminated fibromyalgia cases from rheumatoid arthritis and healthy individuals even when current clinical pain was included in the analysis. Combining fatigue, insomnia, and SREP led to near perfect diagnostic accuracy (99%) in differentiating fibromyalgia from healthy individuals and 86.3% accuracy in discriminating fibromyalgia from rheumatoid arthritis. CONCLUSIONS: These results provide further evidence of SREP as a marker of pain sensitization in fibromyalgia and suggest that it captures aspects of fibromyalgia not fully captured by clinical features. Combining SREP with assessment of clinical features could potentially improve fibromyalgia diagnosis.

Slowly Repeated Evoked Pain as a Marker of Central Sensitization in Fibromyalgia: Diagnostic Accuracy and Reliability in Comparison With Temporal Summation of Pain.

OBJECTIVE: This study examined the diagnostic accuracy and test-retest reliability of a novel dynamic evoked pain protocol (slowly repeated evoked pain [SREP]) compared with temporal summation of pain (TSP), a standard index of central sensitization. METHODS: Thirty-five fibromyalgia (FM) patients and 30 rheumatoid arthritis (RA) patients completed, in pseudorandomized order, a standard mechanical TSP protocol (10 stimuli of 1-second duration at the thenar eminence using a 300-g monofilament with 1 second interstimulus interval) and the SREP protocol (9 suprathreshold pressure stimuli of 5-second duration applied to the fingernail with a 30-second interstimulus interval). To evaluate reliability for both protocols, they were repeated in a second session 4-7 days later. RESULTS: Evidence for significant pain sensitization over trials (increasing pain intensity ratings) was observed for SREP in FM (p < .001) but not in RA (p = .35), whereas significant sensitization was observed in both diagnostic groups for the TSP protocol (p < .008). Compared with TSP, SREP demonstrated higher overall diagnostic accuracy (87.7% versus 64.6%), greater sensitivity (0.89 versus 0.57), and greater specificity (0.87 versus 0.73) in discriminating between FM and RA patients. Test-retest reliability of SREP sensitization was good in FM (intraclass correlations = 0.80), and moderate in RA (intraclass correlations = 0.68). CONCLUSIONS: SREP seems to be a dynamic evoked pain index tapping into pain sensitization that allows for greater diagnostic accuracy in identifying FM patients compared with a standard TSP protocol. Further research is needed to study mechanisms underlying SREP and the potential utility of adding SREP to standard pain evaluation protocols.

Is Resolution of Chronic Pain Associated With Changes in Blood Pressure-related Hypoalgesia?

Background: In healthy individuals, elevated resting blood pressure (BP) is associated with reduced pain responsiveness and lower temporal summation. Prior work indicates that this BP-related hypoalgesia is reduced in individuals with chronic pain. Purpose: This study evaluated whether resolution of chronic pain was associated with greater BP-related hypoalgesia compared to nonresolution. Methods: From a prospective sample of adolescents and young adults diagnosed with chronic functional abdominal pain an average of 9 years earlier, 99 individuals in whom the condition had resolved and 51 individuals with ongoing abdominal pain were studied. Resting systolic BP was assessed, followed by evaluation of thermal pain threshold and tolerance, and assessment of temporal summation to thermal pain stimuli. Results: Higher resting systolic BP was significantly associated with higher pain threshold and tolerance, and lower temporal summation only in the group with resolved functional abdominal pain (p < .05). Hierarchical regressions revealed that interactions between BP and resolution of chronic pain were significant only for pain tolerance (p < .05). Analyses by sex indicated that interactions between BP and resolution status were significant for the temporal summation outcome in males but not in females. Conclusions: Results suggest that BP-related hypoalgesic mechanisms may be more effective in individuals in whom chronic pain has resolved compared to those with ongoing chronic pain. Findings hint at sex differences in the extent to which resolution of chronic pain is associated with BP-related hypoalgesia. Whether greater BP-related hypoalgesia is a consequence of, or alternatively a contributor to, resolution of chronic pain warrants further investigation.

Responses to Slowly Repeated Evoked Pain Stimuli in Fibromyalgia Patients: Evidence of Enhanced Pain Sensitization.

OBJECTIVE: The pathophysiology of fibromyalgia has been related to central pain sensitization. This study tested a laboratory protocol evaluating responses to slowly repeated evoked pain stimuli (SREP) that may index central pain sensitization in fibromyalgia. DESIGN: A between-subjects controlled laboratory study. SUBJECTS: Twenty-four fibromyalgia patients and 24 healthy participants. METHODS: A SREP protocol was administered to all subjects, consisting of a single series of nine low-intensity pressure stimuli of five-second duration and thirty-second interstimulus interval. Subjective evoked pain intensity was assessed with a visual analogical scale. Clinical fibromyalgia pain was assessed with the McGill Pain Questionnaire. RESULTS: Perceived pain intensity increased during the SREP protocol in fibromyalgia patients but not in healthy participants. Neither pain threshold nor pain tolerance was associated with SREP. Degree of SREP sensitization was associated with McGill Pain Questionnaire-Sensory ratings of fibromyalgia pain. The effect size for differences between the fibromyalgia and healthy control groups was greater, and the overlaps of the groups distributions lower, for SREP sensitization than for traditional evoked pain measures of pain threshold and tolerance. SREP demonstrated higher specificity in discriminating fibromyalgia and control groups relative to pain threshold or tolerance. CONCLUSIONS: A protocol employing a single series of nine low-suprathreshold-intensity slowly repeated pain stimuli elicits increased perceived pain in fibromyalgia patients, consistent with central sensitization despite relatively long interstimulus intervals. SREP appears to be more useful than traditional evoked pain threshold tolerance measures in terms of predicting levels of clinical pain and discriminating between fibromyalgia patients and healthy individuals.

Impact of homeostatic body hydration status, evaluated by hemodynamic measures, on different pain sensitization paths to a chronic pain syndrome.

Contrasting findings on the mechanisms of chronic pain and hypertension development render the current conventional evidence of a negative relationship between blood pressure (BP) and pain severity insufficient for developing personalized treatments. In this interdisciplinary study, patients with fibromyalgia (FM) exhibiting clinically normal or elevated BP, alongside healthy participants were assessed. Different pain sensitization responses were evaluated using a dynamic 'slowly repeated evoked pain' (SREP) measure, as well as static pain pressure threshold and tolerance measures. Cardiovascular responses to clino-orthostatic (lying-standing) challenges were also examined as acute re- and de-hydration events, challenging cardiovascular and cerebrovascular homeostasis. These challenges involve compensating effects from various cardiac preload or afterload mechanisms associated with different homeostatic body hydration statuses. Additionally, hair cortisol concentration was considered as a factor with an impact on chronic hydration statuses. Pain windup (SREP) and lower pain threshold in FM patients were found to be related to BP rise during clinostatic (lying) rehydration or orthostatic (standing) dehydration events, respectively. These events were determined by acute systemic vasoconstriction (i.e., cardiac afterload response) overcompensating for clinostatic or orthostatic cardiac preload under-responses (low cardiac output or stroke volume). Lower pain tolerance was associated with tonic blood pressure reduction, determined by permanent hypovolemia (low stroke volume) decompensated by permanent systemic vasodilation. In conclusion, the body hydration status profiles assessed by (re)activity of systemic vascular resistance and effective blood volume-related measures can help predict the risk and intensity of different pain sensitization components in chronic pain syndrome, facilitating a more personalized management approach.

Pain sensitisation in patients with sickle cell disease: A preliminary study.

BACKGROUND: Responses to experimental pain have suggested central and peripheral sensitisation in adult patients with sickle cell disease (SCD). Recent studies have proposed an algometry-derived dynamic measure of pain sensitisation, slowly repeated evoked pain (SREP), which is useful in the discrimination of painful conditions related to central sensitisation. Pain and fatigue are two symptoms that affect the general functioning of patients with SCD most significantly, however, research about experimental dynamic pain measures and their relation to the main symptoms of SCD (pain and fatigue) is still scarce. OBJECTIVE: This preliminary study aimed to test the utility of the SREP protocol for detecting pain sensitisation in patients with SCD, and to evaluate the associations of pain sensitisation, pain threshold, and pain tolerance with the main clinical symptoms of SCD, pain and fatigue. METHODS: Twenty-two female outpatients with SCD and 20 healthy women participated. Pain threshold, pain tolerance, and pain sensitisation were assessed by algometry in the fingernail. Clinical pain, fatigue, anxiety, depression and pain catastrophizing were evaluated. RESULTS: No group differences were found in pain threshold and tolerance. However, using the SREP protocol, pain sensitisation was greater in patients than in healthy participants, even after controlling for psychological variables and body mass index. Pain threshold and tolerance were inversely associated with fatigue levels in the SCD group, with pain tolerance being the main predictor. CONCLUSIONS: Pain threshold and tolerance did not discriminate between patients and healthy individuals, but were useful for predicting fatigue severity in SCD. The SREP protocol provides a useful dynamic measure of pain for the discrimination and detection of enhanced pain sensitisation in patients with SCD, which could contribute to more personalised pain evaluations and treatment for these patients.

Online ACT intervention for fibromyalgia: An exploratory study of feasibility and preliminary effectiveness with smartphone-delivered experiential sampling assessment.

Introduction: Acceptance and commitment therapy (ACT) is an effective treatment for chronic pain conditions. ACT seeks to produce clinical change by enhancing Psychological Flexibility (PF). This exploratory (feasibility and preliminary effectiveness) study presents a pilot application of an online ACT group intervention for fibromyalgia (FM) with an extensive Experiential Sampling (ES) assessment of outcome and process variables via smartphone. Method: 5-weekly ACT online group sessions were applied to 9 female FM patients. Questionnaire-based assessments of several clinical outcomes and PF processes were conducted pre- and post-intervention, and at 6-month follow-up. Extensive (6 weeks pre- and 6 weeks post-intervention) smartphone-delivered ES was implemented to gather process and outcome data in the patients' usual contexts. Clinically significant change was evaluated both at the group level and individually. Results: This treatment format appears to be feasible and acceptable to participants, with good adoption and completion rates (75 %) and excellent rates of treatment completion and clinical adherence (100 %). Participants showed significant reductions in affective pain, distress and biopsychosocial impact of FM both post-intervention and at 6-month follow-up (as measured with questionnaires), as well as significant improvements in satisfaction with actions and emotional discomfort (as measured through ES). Multilevel regression analyses indicated that PF-related processes assessed through ES had a significant impact on clinical outcomes and predicted the impact of FM at the 6-month follow-up. Conclusions: A brief online group ACT intervention for FM was both feasible and acceptable to participants. Also, there was preliminary evidence of effectiveness in enhancing pain-related PF and producing clinical benefits in FM.

Algometry for the assessment of central sensitisation to pain in fibromyalgia patients: a systematic review.

INTRODUCTION: The pathophysiology of fibromyalgia (FM) is related to central sensitisation (CS) to pain. Algometry allows assessing CS based on dynamic evoked pain. However, current algometrýs protocols require optimising, unifying and updating. OBJECTIVES: 1) identify the dynamic pain measures used most frequently to effectively assess CS processes in FM, and 2) consider the future of the algometry assessing CS in these patients. METHODS: Cochrane Collaboration guidelines and PRISMA statements were followed. The protocol was registered in PROSPERO database (ID: CRD42021270135). The selected articles were evaluated using the Cochrane risk of bias (ROB) assessment tool. The PubMed, Scopus, and Web of Science databases were searched. RESULTS: Thirty-four studies were selected, including measures such as temporal summation of pain (TSP), aftersensations (AS), spatial summation of pain (SSP), the noxious flexion reflex (NFR) threshold, conditioned pain modulation (CPM), cutaneous silent period (CuSP), and slowly repeated evoked pain (SREP); and evoked pain combined with neuroimaging. Each measure offered various advantages and limitations. According to ROB, 28 studies were of low quality, 3 of moderate quality, and 3 of high quality. CONCLUSIONS: Several pain indicators have been demonstrated to successfully examine CS involvement in FM in the last years. Algometry, especially when it involves diverse body sites and tissues, might provide further insight into (1) the evaluation of psychological factors known to influence pain experience, (2) new dynamic pain indicators, and (3) the simultaneous use of certain neuroimaging techniques. Further research clarifying the mechanisms underlying some of these measures, and homogenisation and optimisation of the algometrýs protocols, are needed. KEY MESSAGESAlgometry allows for assessing Central Sensitisation by applying dynamic evoked pain.The future of algometry could relapse in its combination with neuroimaging.Recently-emerged pain indicators should be considered for algometrýs new protocols.

Narcissistic Personality and Its Relationship with Post-Traumatic Symptoms and Emotional Factors: Results of a Mediational Analysis Aimed at Personalizing Mental Health Treatment.

BACKGROUND: Narcissism is characterized by entitlement, grandiose fantasies and the need for admiration. This personality trait has been associated with both traumatic experiences and emotional problems. Most studies have only focused on narcissism in the context of childhood trauma and negative emotional factors. However, dimensions of grandiose narcissism such as authority have been linked to adaptive outcomes. Furthermore, narcissism might not be linked only to negative childhood experiences; it may also be associated with the presence of post-traumatic symptoms. Therefore, the present study aimed to assess the associations between narcissism and the frequency and severity of post-traumatic symptoms and emotional factors (resilience capacity, emotional regulation, positive and negative affect, intolerance of uncertainty and perceived stress), as well as the possible mediational role of the latter in the relationship between narcissism and post-traumatic symptoms. METHOD: A total of 115 healthy young psychology undergraduates and their relatives, aged from 18 to 40 years, were asked to complete a set of questionnaires to evaluate the aforementioned variables. RESULTS: The results showed that most of the grandiose narcissism dimensions were positively related to emotional adaptive outcomes, except exploitativeness and entitlement. The negative associations observed between the frequency and severity of post-traumatic symptoms and narcissism (self-sufficiency) were mediated by affect and resilience, which were in turn positively associated with the majority of the narcissism dimensions. Both positive affect and resilience were important factors mediating the association between grandiose narcissism and post-traumatic symptoms. CONCLUSIONS: Our findings reaffirm the need to assess not only desirable personality traits, but also ones that are not initially desirable, before pathologizing them. This consideration may be essential to achieve a personalized approach to the prevention of mental health problems, and promotion of positive emotions, in the general population.

Slowly repeated evoked pain (SREP) as a central sensitization marker in episodic migraine patients.

Migraine headache is a pain condition characterized by severe and recurrent unilateral head pain. Among other mechanisms, central pain sensitization processes seem to be involved in the disorder. An experimental protocol based on slowly repeated evoked pain (SREP) has been shown to indicate pain sensitization in fibromyalgia patients and differentiate these patients from healthy individuals and rheumatoid arthritis patients. This study examined SREP sensitization in migraine patients and explored its potential usefulness as a central sensitization marker. The SREP protocol was administered to 40 episodic migraine (EM) patients not currently experiencing a headache and 40 healthy controls. SREP consisted of a series of 9 suprathreshold painful pressure stimuli of 5 s duration and a 30 s interstimulus interval. SREP sensitization was indexed by the increase in pain ratings across the stimuli. Pain threshold, pain tolerance and temporal summation of pain were also assessed. SREP sensitization was observed in EM, but not in healthy individuals (p < .001). SREP differentiated between EM and healthy individuals with up to 75% diagnostic accuracy. Pain threshold, pain tolerance and temporal summation of pain did not show significant discriminative ability. An SREP index value of 0.5 was the most sensitive cut-off for detecting central pain sensitization when prioritizing diagnostic sensitivity (0.88). Results provide evidence for SREP as a possible central sensitization marker with potential clinical utility in migraine patients. Inclusion of SREP in Quantitative Sensory Testing protocols may enhance the assessment of altered pain modulation in different pain conditions.

The cardiac, vasomotor, and myocardial branches of the baroreflex in fibromyalgia: Associations with pain, affective impairments, sleep problems, and fatigue.

This study investigated the cardiac, vasomotor, and myocardial branches of the baroreflex in fibromyalgia using the spontaneous sequence method. Systolic blood pressure (SBP), interbeat interval (IBI), stroke volume (SV), pre-ejection period (PEP), and total peripheral resistance (TPR) were continuously recorded in 40 fibromyalgia patients and 30 healthy individuals during a cold pressor test and a mental arithmetic task. Sequences of covariation between SBP and IBI (cardiac branch), SV and PEP (myocardial branch), and TPR (vasomotor branch) were identified. Baroreflex sensitivity (BRS) was represented by the slope of the regression line between values in the sequences; baroreflex effectiveness (BEI) was indexed by the proportion of progressive SBP changes that elicited reflex responses. Patients exhibited lower BRS in the three branches, lower BEI in the cardiac and vasomotor branches, and reduced reactivity in cardiac BRS and BEI, SBP, IBI, SV, and PEP. Moreover, BRS and BEI were inversely related to clinical pain, cold pressor pain, depression, trait anxiety, sleep problems, and fatigue. Reduced function of the three baroreflex branches implies diminished resources for autonomic inotropic, chronotropic, and vascular regulation in fibromyalgia. Blunted stress reactivity indicates a limited capacity for autonomic cardiovascular adjustment to situational requirements. The associations of BRS and BEI with pain perception may reflect the antinociceptive effects arising from baroreceptor afferents, where reduced baroreflex function may contribute to the hyperalgesia characterizing fibromyalgia. The associations with affective impairments, sleep problems, and fatigue suggest that baroreflex dysfunctions are also involved in the secondary symptoms of the disorder.

Effectiveness of Acceptance and Commitment Therapy in Central Pain Sensitization Syndromes: A Systematic Review.

OBJECTIVES: Acceptance and commitment therapy (ACT) is considered by the American Psychological Association as an evidence-based treatment for a variety of disorders, including chronic pain. The main objective of the present systematic review was to determine the effectiveness of ACT in patients with central pain sensitization syndromes (CPSS). METHODS: This systematic review was conducted according to the guidelines of the Cochrane Collaboration and PRISMA statements. The protocol was registered in advance in the Prospective Register of Systematic Reviews (PROSPERO) international database. The selected articles were evaluated using the Cochrane risk of bias (ROB) assessment tool. The PubMed, Scopus, and Web of Science databases were searched. RESULTS: The literature search identified 21 studies (including investigations of fibromyalgia syndrome, irritable bowel syndrome, and migraine) eligible for the systematic review. There were no studies regarding the effectiveness of ACT for chronic tension-type headache (CTTH), interstitial cystitis (IC), or temporomandibular disorder (TMD). The evaluation of ROB showed that 12 of the selected studies were of low quality, 5 were of moderate quality, and 4 were high quality. ACT reduces some clinical symptoms, such as anxiety, depression, and pain. This positive effect of ACT might be mediated by pain acceptance, psychological flexibility, optimism, self-efficacy, or adherence to values. ACT showed better results in comparison to non-intervention (e.g., "waiting list") conditions, as well as pharmacological and psychoeducational interventions. It is not entirely clear whether extended ACT treatments are more advantageous than briefer interventions. CONCLUSIONS: There are few studies about the effectiveness of ACT on CPSS. However, ACT seems to reduce subjective CPSS symptoms and improve the health-related quality of life of these patients. The absence of studies on the effectiveness of ACT in CTTH, IC, and TMD, indicate the pressing need for further ACT studies in these CPSS.

Attentional function in fibromyalgia and rheumatoid arthritis.

Concentration difficulties, forgetfulness and mental slowness are common in fibromyalgia syndrome (FMS); initial findings suggest that rheumatoid arthritis (RA) may also be accompanied by cognitive impairments. This study aimed to compare attentional performance between patients with FMS and RA. Attention was quantified in the domains of alerting, orienting and executive control using the Attentional Network Test-Interaction (ANT-I) in 56 women with FMS, 41 women with RA and 50 healthy women. Pain severity was statistically controlled in the group comparison. While FMS patients exhibited longer reaction times and made more errors on the ANT-I than RA patients and healthy women, performance did not differ between RA patients and healthy women. The magnitude of group differences did not vary by the experimental conditions of the ANT-I, suggesting a general attentional deficit in FMS rather than specific impairments in the domains of alerting, orienting and executive control. Differences between patient groups may relate to the different pathogenetic mechanisms involved in the disorders, i.e. inflammatory processes in RA and central nervous sensitization in FMS. In FMS, heightened activity in the pain neuromatrix may interfere with attention, because it requires enhanced neural resources in brain areas that are involved in both pain and attentional processing.

Correction: Reduced activity, reactivity and functionality of the sympathetic nervous system in fibromyalgia: An electrodermal study.

[This corrects the article DOI: 10.1371/journal.pone.0241154.].

Reduced activity, reactivity and functionality of the sympathetic nervous system in fibromyalgia: An electrodermal study.

Alterations in autonomic activity are well established in fibromyalgia syndrome (FMS). Previous studies found reduced parasympathetic activity and sympathetic reactivity to physical and stress manipulations. However, sympathetic activity at rest has not been well studied in FMS. Sweating is exclusively controlled by sympathetic mechanisms. In this study, skin conductance (SC), as an indirect measure of sweating, was analyzed in 45 women with FMS and 38 healthy women. Tonic SC levels were recorded during a 4-minute rest period, and a breathing maneuver consisting of deep breathing with posterior breath holding was used to evoke SC responses. Associations of tonic SC with state anxiety and body temperature, measured in the hand, were explored to determine sweat functionality. The results showed reduced tonic SC levels, with a less marked decrease in SC during the recording period, and blunted SC reactivity to the breathing manipulation in FMS patients relative to healthy participants. Positive associations of SC with state anxiety and body temperature were observed in healthy participants, but these associations were absent in FMS patients. These results indicate alterations of sweating in FMS, suggesting reduced tonic and reactivity sympathetic influences. Furthermore, the absence of associations between SC levels and state anxiety and body temperature in the patient sample suggested a loss of functionality of the autonomic nervous system in FMS. Diminished autonomic regulation in FMS would reduce the ability to cope with environmental demands, thus favoring increases in stress and pain levels. Finally, the observed reduction in sweating is in accordance with evidence of small nerve fiber neuropathy in FMS.

Reliability, Factor Structure and Predictive Validity of the Widespread Pain Index and Symptom Severity Scales of the 2010 American College of Rheumatology Criteria of Fibromyalgia.

Fibromyalgia syndrome (FMS) is a chronic condition of widespread pain. In 2010, the American College of Rheumatology (ACR) proposed new diagnostic criteria for FMS based on two scales: the Widespread Pain Index (WPI) and Symptoms Severity (SS) scale. This study evaluated the reliability, factor structure and predictive validity of WPI and SS. In total, 102 women with FMS and 68 women with rheumatoid arthritis (RA) completed the WPI, SS, McGill Pain Questionnaire, Trait Anxiety Inventory, Fatigue Severity Scale, Oviedo Quality of Sleep Questionnaire, and Beck Depression Inventory. Pain threshold and tolerance and a measure of central sensitization to pain were obtained by pressure algometry. Values on WPI and SS showed negative-skewed frequency distributions in FMS patients, with most of the observations concentrated at the upper end of the scale. Factor analysis did not reveal single-factor models for either scale; instead, the WPI was composed of nine pain-localization factors and the SS of four factors. The Cronbach's α (i.e., Internal consistency) was 0.34 for the WPI,0.83 for the SS and 0.82 for the combination of WPI and SS. Scores on both scales correlated positively with measures of clinical pain, fatigue, insomnia, depression, and anxiety but were unrelated to pain threshold and tolerance or central pain sensitization. The 2010 ACR criteria showed 100% sensitivity and 81% specificity in the discrimination between FMS and RA patients, where discrimination was better for WPI than SS. In conclusion, despite their limited reliability, both scales allow for highly accurate identification and differentiation of FMS patients. The inclusion of more painful areas in the WPI and of additional symptoms in the SS may reduce ceiling effects and improve the discrimination between patients differing in disease severity. In addition, the use of higher cut-off values on both scales may increase the diagnostic specificity in Spanish samples.

Blood pressure-related pain modulation in fibromyalgia: Differentiating between static versus dynamic pain indicators.

INTRODUCTION: Resting blood pressure (BP) has been found to be inversely associated with evoked pain responsiveness in healthy populations. However, some reports suggest that BP-related pain modulation may be dysfunctional in chronic pain patients. This study examined whether BP-related pain modulation, indexed by both static and dynamic evoked pain responses, is altered in fibromyalgia (FM) patients compared to pain-free individuals. METHOD: Pain threshold and tolerance as static evoked pain measures and slowly repeated evoked pain (SREP) as a dynamic evoked pain index were measured in 30 FM patients and 27 healthy controls. BP was continuously recorded throughout a 5 minute pre-pain rest period. RESULTS: SREP sensitization was observed only in the FM group. Higher BP predicted elevated pain threshold and tolerance in healthy individuals, but not in FM. Conversely, BP was inversely associated with SREP sensitization in FM whereas no association was found in healthy controls. CONCLUSIONS: Static evoked pain measures suggested BP-related pain inhibitory dysfunction in FM. In contrast, for pain sensitization as indexed by SREP, FM displayed the expected BP-related inhibitory effects. BP-related pain modulation is manifested in FM differentially for static versus dynamic pain indicators. Use of both types of evoked pain measures may be valuable in the study of mechanisms underlying altered pain modulatory systems in FM.

Time domain measurement of the vascular and myocardial branches of the baroreflex: A study in physically active versus sedentary individuals.

This study tests the spontaneous sequence method for the evaluation of the cardiac, vasomotor, and myocardial branches of the baroreflex. Systolic blood pressure (SBP), interbeat interval (IBI), stroke volume (SV), preejection period (PEP), and total peripheral resistance (TPR) were continuously recorded in 33 physically active and 25 sedentary participants at rest and during a mental arithmetic task. Sequences of spontaneous covariation between SBP and IBI (for the cardiac branch), SV and PEP (for the myocardial branch), and TPR (for the vasomotor branch) were located. The slope of the regression line between values in the sequences produced an estimate of baroreflex sensitivity (BRS), and the proportion of progressive SBP changes that elicited reflex modulations yielded an estimate of baroreflex effectiveness (BEI). The active group showed greater BRS in all three branches than the sedentary group. Cardiac and vasomotor BEI decreased during the arithmetic task in the sedentary group but not in the active one. Only cardiac BRS decreased during the arithmetic task. In conclusion, the method appears appropriate for the simultaneous assessment of the three baroreflex branches. The assessment of the vascular branch of the baroreflex may have prognostic relevance in the development of hypertension or other cardiometabolic diseases.